Introduction: In this experiment we will be using an aromatic organic compound, this compound is the primary element of the extract of the vanilla bean. Through the use of an alcohol as a solvent and oxidizing agents as Sodium hypochlorite solution 6%w/w (common bleach) with sodium iodide. We will be halogenating vanillin during the lab procedure, Vanillin or 4-hydroxy-3-methoxybenzaldehyde will undergo an electrophilic substitution reaction in this experiment. Aromatic compounds most often undergo through electrophilic substitution reactions rather than nucleophilic substitution reactionsthis is because aromatic rings are more stable due to resonance. Essentially these reactions occur via a two-step addition-elimination process, in which the electrophilic component first adds to the aromatic ring by attaching itself to the π electrons, forming a cationic intermediate which then eliminates a leaving group (usually a proton) to produce the substituted product.
Procedure: The procedure came from Doxsee, K. M.; Hutchison, J. E. Green Organic Chemistry - Strategies, Tools, and Laboratory Experiments, Print 2004; (p.186-187). Step number 7. and Gilbertson, R.; Parent, K. E.; McKenzie, L. C.; Hutchison, J. E. Electrophilic Aromatic Iodination of 4'-Hydroxyacetophenone Greener Approaches to Undergraduate Chemistry Experiments, Print Kirchhoff, M., Ryan, M., Eds.; American Chemical Society: Washington D.C., 2002; (p.1-3).
*Adaptations included the use of vanillin instead of 4' Hydroxyacetophenone.
Data: Initial measurements for the reaction: In a 100ml round-bottom flask containing a magnetic stir bar, add 1.01g of vanillin (White or very slightly yellow needles) in 20ml of ethanoln. Then 1.2g of sodium iodide (creamy color, powdery) was added. After adding sodium iodine cool down with an ice/water bath. With the use of a separatory funnel, drop-wise 11ml of Sodium hypochlorite solution (6% w/w bleach) for 10min. The solution changed color from pale yellow to red-brownish.
The solution was warmed up at room temperature (22.5 Celsius) and stirred for 10 minutes.
Workup and Isolation: After Adding 10 ml of sodium thiosulfate solution (10% w/w) the Ph was 8. Then acidifying the solution with 4.5 ml of Hydrochloric acid (10% w/w) getting a Ph of 2 (turning yellowish). Remove the ethanol from suspension on rotary evaporator, for less than 10 minutes
The flask cooled for 10 minutes Proceed to vacuum filtration for about 8 minutes. The weight of the crude product was 2.89g The crude product was placed in a 125ml Erlenmeyer flask and heated. 25 ml of 2-propanol was added to generate a clear solution. After allowing the solution to cool and proceed with vacuum filtration 0.001grams of crystals were collected.
Melting Point Data Experimental Melting Point: 151.8-152.3C Literature Melting Point: 183-185C
Conclusion: The goal of the experiment was to promote an aromatic compound to react via an electrophilic substitution. The introduction of bleach and sodium iodide worked as oxidizing reagents. Thus, yielding a pure product of Iodovanillin. The experimental melting point ranged from 151.8-152.3C this is lower than the 183-185C recorded melting point of Iodovanillin. Possible reasons for the lower melting point could have been the addition of impurities into the experiment, perhaps unclean glass wear. Possible reasons for the small amount of .001g crystals formed may be attributed to the use of too much solvent. Over adding solvent can cause the loss of the more soluble compound in a solution, resulting in a lack of crystal formation and altered molecular characteristics of the final product. Continued stirring while adding the solvent could have delayed the observation that the solution cloudiness was clearing, this could have caused the addition of too much solvent. Suggestions for repeating this experiment include allowing the solution to heat slowly as the solvent is added during the recrystallization process. In addition allow the solution to settle and be observed before adding more solvent. This technique will allow for any cloudiness caused by turbidity to settle.
Post-Lab Q this week’s Elimination lab: Calculate the atom economy for this reaction. Atom economy is defined on Wikipedia, but essentially is the molecular weight of the desired product divided by the moles of all reactants (don’t include catalysts or solvents in our reaction).
Molecular weight of Iodovanillin is 278.04g Moles of reactants: Sodium iodide 149.90g + Vanillin 152.19g + Sodium hypochlorite 74.44 278.04/376.53 x 100 =Atom Economy= 74%
This report earned the following scores: format (2/2) style (0.5/2) data (1.5/3) quality of result (0.5/1) quality of reported data (0.5/1) conclusion (1/2) error (1/1) post-lab Q (0.5/2) for a total of 7.5/14. LOTS of room for improvement. The report gives the impression that it was done in a hurry, and without much editing. You are all responsible together for peer reviewing the report, and the effort will pay off for everyone.
Introduction:
In this experiment we will be using an aromatic organic compound, this compound is the primary element of the extract of the vanilla bean. Through the use of an alcohol as a solvent and oxidizing agents as Sodium hypochlorite solution 6%w/w (common bleach) with sodium iodide. We will be halogenating vanillin during the lab procedure, Vanillin or 4-hydroxy-3-methoxybenzaldehyde will undergo an electrophilic substitution reaction in this experiment. Aromatic compounds most often undergo through electrophilic substitution reactions rather than nucleophilic substitution reactionsthis is because aromatic rings are more stable due to resonance. Essentially these reactions occur via a two-step addition-elimination process, in which the electrophilic component first adds to the aromatic ring by attaching itself to the π electrons, forming a cationic intermediate which then eliminates a leaving group (usually a proton) to produce the substituted product.
Electrophilic Aromatic Iodination of vanillin or 4-Hydroxyacetophenone with bleach and NaI(p.173-179)
*Aromatic Iodination of vanillin image taken from: http://science.widener.edu/svb/olcc_safety/papers/hutchison.pdf
Procedure:
The procedure came from Doxsee, K. M.; Hutchison, J. E. Green Organic Chemistry - Strategies, Tools, and Laboratory Experiments, Print 2004; (p.186-187). Step number 7. and Gilbertson, R.; Parent, K. E.; McKenzie, L. C.; Hutchison, J. E. Electrophilic Aromatic Iodination of 4'-Hydroxyacetophenone Greener Approaches to Undergraduate Chemistry Experiments, Print Kirchhoff, M., Ryan, M., Eds.; American Chemical Society: Washington D.C., 2002; (p.1-3).
*Adaptations included the use of vanillin instead of 4' Hydroxyacetophenone.
Data:
Initial measurements for the reaction:
In a 100ml round-bottom flask containing a magnetic stir bar, add 1.01g of vanillin (White or very slightly yellow needles) in 20ml of ethanoln. Then
1.2g of sodium iodide (creamy color, powdery) was added. After adding sodium iodine cool down with an ice/water bath.
With the use of a separatory funnel, drop-wise 11ml of Sodium hypochlorite solution (6% w/w bleach) for 10min. The solution changed color from pale yellow to red-brownish.
The solution was warmed up at room temperature (22.5 Celsius) and stirred for 10 minutes.
Workup and Isolation: After Adding 10 ml of sodium thiosulfate solution (10% w/w) the Ph was 8. Then acidifying the solution with 4.5 ml of Hydrochloric acid (10% w/w) getting a Ph of 2 (turning yellowish).
Remove the ethanol from suspension on rotary evaporator, for less than 10 minutes
The flask cooled for 10 minutes
Proceed to vacuum filtration for about 8 minutes. The weight of the crude product was 2.89g
The crude product was placed in a 125ml Erlenmeyer flask and heated. 25 ml of 2-propanol was added to generate a clear solution. After allowing the solution to cool and proceed with vacuum filtration 0.001grams of crystals were collected.
Melting Point Data
Experimental Melting Point: 151.8-152.3C
Literature Melting Point: 183-185C
Conclusion:
The goal of the experiment was to promote an aromatic compound to react via an electrophilic substitution. The introduction of bleach and sodium iodide worked as oxidizing reagents. Thus, yielding a pure product of Iodovanillin. The experimental melting point ranged from 151.8-152.3C this is lower than the 183-185C recorded melting point of Iodovanillin. Possible reasons for the lower melting point could have been the addition of impurities into the experiment, perhaps unclean glass wear. Possible reasons for the small amount of .001g crystals formed may be attributed to the use of too much solvent. Over adding solvent can cause the loss of the more soluble compound in a solution, resulting in a lack of crystal formation and altered molecular characteristics of the final product. Continued stirring while adding the solvent could have delayed the observation that the solution cloudiness was clearing, this could have caused the addition of too much solvent. Suggestions for repeating this experiment include allowing the solution to heat slowly as the solvent is added during the recrystallization process. In addition allow the solution to settle and be observed before adding more solvent. This technique will allow for any cloudiness caused by turbidity to settle.
Post-Lab Q this week’s Elimination lab:
Calculate the atom economy for this reaction. Atom economy is defined on Wikipedia, but essentially is the molecular weight of the desired product divided by the moles of all reactants (don’t include catalysts or solvents in our reaction).
Molecular weight of Iodovanillin is 278.04g
Moles of reactants: Sodium iodide 149.90g + Vanillin 152.19g + Sodium hypochlorite 74.44
278.04/376.53 x 100 =Atom Economy= 74%
This report earned the following scores: format (2/2) style (0.5/2) data (1.5/3) quality of result (0.5/1) quality of reported data (0.5/1) conclusion (1/2) error (1/1) post-lab Q (0.5/2) for a total of 7.5/14. LOTS of room for improvement. The report gives the impression that it was done in a hurry, and without much editing. You are all responsible together for peer reviewing the report, and the effort will pay off for everyone.